The preparation of enzymatically active tubes is proposed for use in physiological studies and extracorporeal circulation systems. Brinase, L-phenylalanine ammonia lyase and carboxypeptidase G-1, which have possible application in cancer therapy would be immobilized on the tube innerwall in a gel or a porous support layer. The study of the kinetic properties and the stability of these enzyme tubes in vitro would enable us to assess the potential of such biochemical reactors and would supply the data for ensuing clinical investigations. The results would be applied to optimum design of such reactors for use as extracorporeal shunts. Another aspect of this study is the augmentation of the active life of the aforementioned enzymes and L-asparaginase in therapeutic use. For this soluble polymer-bound and intramolecularly crosslinked derivatives of these enzymes would be prepared and their stability and enzymic properties investigated.